The present invention is an improved insulative end cap for cylindrical metal drying rollers of paper drying machines; a composition of matter for use in providing such insulative end caps of cylindrical metal drying rollers of paper drying machines; and a method of manufacture of insulative end caps for cylindrical metal drying rollers of paper drying machines.
Conventional paper drying machines include a plurality of cylindrical metal drying rollers over which continuous sheets of paper are passed to dry the paper as one of the final steps in the manufacture of paper. The cylindrical metal drying rollers are generally hollow and such cylindrical metal drying rollers are heated by the introduction of high-temperature and high-pressure steam into the hollow interior of the cylindrical metal drying rollers. The introduction of such high-temperature and high-pressure steam is provided in order to heat the drying surfaces of the cylindrical metal drying rollers.
A problem commonly encountered in such cylindrical drying rollers is the loss of a substantial amount of energy through the metallic end caps of the cylindrical metal drying rollers. The metal used to manufacture such conventional end caps does not generally have good insulative properties, and the temperature of the high-pressure and high-temperature steam within the cylindrical metal drying roller is often as high as 320.degree. Fahreinheit, and the outside air temperature adjacent the paper drying machine is generally at room temperature. Such substantial difference between the temperature on the inside of the metal end cap and the temperature on the outside of the metal end cap of the cylindrical metal drying roller, combined with the poor insulative qualities of the metal presently conventionally used as the end caps for such cylindrical metal drying rollers, results in high rate of heat loss through the end caps and a substantial waste of energy.
A large paper drying machine may include up to one hundred such cylindrical drying rollers. Additionally, such paper drying machines often operate continuously during the paper manufacturing process. Accordingly, the heat lost from such a substantial number of cylindrical metal drying rollers operated continuously in the paper manufacturing process results in substantial and significant additional manufacturing costs due to the additional energy required to replace energy wasted by heat loss through the metal end caps of the cylindrical metal drying rollers of the machine.